α-Galactosidase and Sucrose-Kinase Relationships in a Bi-functional AgaSK Enzyme Produced by the Human Gut Symbiont E1.

Plant α-galactosides belonging to the raffinose family oligosaccharides (RFOs) and considered as prebiotics, are commonly degraded by α-galactosidases produced by the human gut microbiome. In this environment, the E1 symbiont-well-known for various benefit-is able to produce an original AgaSK bifunctional enzyme. This enzyme contains an hydrolytic α-galactosidase domain linked to an ATP dependent extra-domain, specifically involved in the α-galactoside hydrolysis and the phosphorylation of the glucose, respectively.

Sucrose 6-phosphate phosphorylase: a novel insight in the human gut microbiome.

The human gut microbiome plays an essential role in maintaining human health including in degradation of dietary fibres and carbohydrates further used as nutrients by both the host and the gut bacteria. Previously, we identified a polysaccharide utilization loci (PUL) involved in sucrose and raffinose family oligosaccharide (RFO) metabolism from one of the most common Firmicutes present in individuals, Ruminococcus gnavus E1. One of the enzymes encoded by this PUL was annotated as a putative sucrose phosphate phosphorylase (RgSPP).

Rovibrational laser jet-cooled spectroscopy of SF-rare gas complexes in the ν region of SF.

High resolution infrared spectroscopy combining an external cavity quantum cascade laser with a pulsed pin hole supersonic jet is used to investigate small van der Waals (vdW) heteroclusters containing SF6 and rare gas (Rg) atoms in the ν3 region of SF6. In the first step of the analysis, the rovibrational band contours of parallel and perpendicular transitions of 1 : 1 SF6-Rg heterodimers (Rg = Ar, Kr, Xe) are simulated to derive ground and excited state parameters and hence ground state and equilibrium S-Rg distances with a precision better than 0.5 pm.

Conformational landscape of the SF dimer as revealed by high resolution infrared spectroscopy and complexation with rare gas atoms.

Taking advantage of a versatile set-up, combining pulsed pin hole or slit nozzle supersonic expansion with an external cavity quantum cascade laser, the rovibrational absorption spectrum of the SF dimer in the ν mode region has been revisited at high resolution under various experimental conditions in SF:He mixtures. Two new rotationally resolved spectral bands have been identified in the range of the parallel band of the dimer spectrum in addition to that previously reported. Among these three spectral features, two of them are assigned to conformations of the dimer (noted #1 and #2), clearly distinguished from their different S-S interatomic distances, i.

Functional analysis of family GH36 α-galactosidases from Ruminococcus gnavus E1: insights into the metabolism of a plant oligosaccharide by a human gut symbiont.

Ruminococcus gnavus belongs to the 57 most common species present in 90% of individuals. Previously, we identified an α-galactosidase (Aga1) belonging to glycoside hydrolase (GH) family 36 from R. gnavus E1 (M.

α-Galactosidase/sucrose kinase (AgaSK), a novel bifunctional enzyme from the human microbiome coupling galactosidase and kinase activities.

α-Galactosides are non-digestible carbohydrates widely distributed in plants. They are a potential source of energy in our daily food, and their assimilation by microbiota may play a role in obesity. In the intestinal tract, they are degraded by microbial glycosidases, which are often modular enzymes with catalytic domains linked to carbohydrate-binding modules.

Comparison of surface and bulk scattering in optical multilayers.

Electromagnetic theories provide a tool to detect the origin of scattering in optical multilayers. Illumination and observation conditions that cause surface and bulk scatterings to have different behaviors are pointed out. Angular, wavelength, and polarization dependences are investigated for the location of structural irregularities at interfaces or in the bulk of a multilayer.